Solid electrolytic capacitor, method for manufacturing solid electrolytic capacitor, and connection element for solid electrolytic capacitor

Abstract

A solid electrolytic capacitor according to the present invention comprises a capacitor element, a sealing body, a first external electrode, and a second external electrode. The capacitor element has: a flat film-like body which includes a valve-acting metal and which has a porous layer having a plurality of holes on the surface of the valve-acting metal; a dielectric layer which is formed on a cathode formation region; and a solid electrolyte layer which is formed on the dielectric layer. Furthermore, the capacitor element has an anode terminal region in which the solid electrolyte layer is not formed on the body and the cathode formation region in which the solid electrolyte layer is formed. The sealing body has a configuration in which a laminate obtained by layering a plurality of the capacitor elements is sealed by an insulating resin. The first external electrode has a blade plate member and a terminal electrode, which is linked to the blade plate member, and is connected to the anode terminal region. The second external electrode is connected to the cathode formation region. The laminate has a first main surface parallel to the capacitor elements and a second main surface facing the first main surface. At least part of the anode terminal region is formed such that the area thereof changes in a stepwise manner in a first direction, which is parallel to the direction of the second main surface, from the first main surface in a plan view of the capacitor element. The anode terminal region and the blade plate member are joined via a melted part of the anode terminal region or the blade plate member.

Description

Solid electrolytic capacitor, method for manufacturing solid electrolytic capacitor, and connection element for solid electrolytic capacitor

[0001] The present invention relates to a solid electrolytic capacitor having a lead frame as an external electrode.

[0002] Various techniques have been known for connecting the anode foil of a laminate formed by stacking multiple capacitor elements to a lead frame. For example, when a lead frame is formed on the bottom surface of a solid electrolytic capacitor, the anode foil is bent and bonded to the lead frame. In this bonding process, the laminate is irradiated with a laser while viewed from above. This melts the lead frame or anode foil. The anode foil is bonded to the lead frame using this melted portion.

[0003] However, using conventional bonding structures presents several problems. More specifically, these are as follows: When bonding the lead frame, the laser is irradiated from the top surface of the laminate toward the bottom surface (in this case, in the direction of gravity). In this case, the lead frame bonded to the capacitor element close to the bottom surface is difficult to melt. That is, it is difficult to uniformly bond the anode foil of the capacitor element to the lead frame. If the bonding between the anode foil of the capacitor element and the lead frame is insufficient, the ESR of the solid electrolytic capacitor increases. Increasing the energy of the laser irradiation improves the melting of the lead frame, but it melts excessively. This can result in molten residue (splash) scattering, potentially causing defects such as short circuits.

[0004] To solve these problems, a technique is known in which through holes (hereinafter referred to as "communicating holes") are provided that communicate with the lead frame and the laminate.

[0005] In Patent Document 1, a through hole is provided in the lead frame and the laminate. By irradiating the inside of the through hole with a laser, the lead frame and the anode foil of the capacitor element melt. This allows the lead frame to be bonded along the surface where the through hole is formed. In other words, the capacitor element near the bottom surface of the laminate is also sufficiently melted, allowing it to be bonded to the lead frame. In addition, splash is contained within the through hole. This prevents short circuits caused by splash.

[0006] In Patent Document 2, a laminate is provided with through holes. The ends of the lead frame and capacitor element melted by laser irradiation flow into the through holes, thereby strengthening the bond between the capacitor element and the lead frame.

[0007] Patent No. 4352802 Patent No. 4930125

[0008] As described above, in Patent Document 1, the through holes are formed using a punch. When forming minute holes in the lead frame or laminate, there is a risk that the anode foil or lead frame of the capacitor element may be damaged. In other words, high-precision processing is required, which increases production costs.

[0009] Furthermore, in the configuration of Patent Document 2, when the capacitor element and the lead frame are joined by laser irradiation, the molten material of the lead frame and the anode foil (the end of the capacitor element) drips downward (in the direction of gravity) from the upper surface. In other words, the molten material accumulates downward, and there is a risk that the capacitor element and the lead frame located near the upper surface will not be sufficiently joined.

[0010] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a solid electrolytic capacitor having improved bonding strength and high reliability.

[0011] The solid electrolytic capacitor of the present invention includes a capacitor element, a sealing body, a first external electrode, and a second external electrode. The capacitor element includes a flat film-like body including a valve metal and a porous layer having a plurality of pores on the surface of the valve metal, a dielectric layer formed on a cathode-forming region, and a solid electrolyte layer formed on the dielectric layer. The capacitor element also includes an anode terminal region on the body where the solid electrolyte layer is not formed, and a cathode-forming region where the solid electrolyte layer is formed. The sealing body is configured to seal a stack of multiple capacitor elements with an insulating resin. The first external electrode includes a blade member and a terminal electrode connected to the blade member, and is connected to the anode terminal region. The second external electrode is connected to the cathode-forming region.

[0012] The laminate has a first main surface parallel to the capacitor element and a second main surface opposite the first main surface. At least a portion of the anode terminal region is formed so that its area changes stepwise in a first direction parallel to the direction from the first main surface to the second main surface when the capacitor element is viewed in plan. The blade member is formed along the anode terminal region. The anode terminal region and the blade member are joined via a fusion portion of the anode terminal region or the blade member.

[0013] In this configuration, when viewed in a plan view from the first main surface to the second main surface (first direction), the anode terminal regions of each capacitor element are arranged so as not to overlap. Furthermore, the blade members are formed along the anode terminal regions. That is, when the capacitor element is placed on a horizontal base with its second main surface as the bottom and the blade members are irradiated with a laser along the first direction, the molten material drips along the anode terminal regions. Therefore, a sufficient molten portion is formed in the anode terminal regions of all capacitor elements included in the laminate. That is, the bonding strength between the blade members and the anode terminal regions via the molten portion is improved. Therefore, the ESR of the solid electrolytic capacitor can be reduced. Furthermore, the high bonding strength allows for a solid electrolytic capacitor that is resistant to thermal shock.

[0014] The method for manufacturing a solid electrolytic capacitor of the present invention includes a capacitor element forming step, a sealing body forming step, a first external electrode forming step, and a second external electrode forming step.

[0015] In the capacitor formation process, a capacitor element is formed, which includes a flat membrane-like main body including a porous layer having a plurality of pores on the surface of the valve metal, a dielectric layer formed on a cathode formation region, and a solid electrolyte layer formed on the dielectric layer, and which includes an anode terminal region where the solid electrolyte layer is not formed on the main body, and a cathode formation region where the solid electrolyte layer is formed. In the sealing body formation process, a laminate of multiple capacitor elements is sealed with an insulating resin. In the first external electrode formation process, a first external electrode is formed, which includes a blade member and a terminal electrode connected to the blade member and is connected to the anode terminal region. In the second external electrode formation process, a second external electrode is formed, which is connected to the cathode formation region.

[0016] In the capacitor element forming step, in a first direction parallel to a first main surface of the laminate parallel to the capacitor element and a second main surface opposite the first main surface, at least a portion of the anode terminal region is formed so that its area changes stepwise in the first direction when the capacitor element is viewed in plan. The vane member is formed along the anode terminal region. The anode terminal region and the vane member are joined via a fusion zone formed by irradiating the vane member with a laser.

[0017] With this manufacturing method, the anode terminal regions of each capacitor element can be formed so as not to overlap when viewed in a plan view in the first direction. Furthermore, the blade members are formed along the anode terminal regions. That is, when the capacitor element is placed on a horizontal base with its second main surface as the bottom and the blade members are irradiated with a laser along the first direction, the molten material drips along the anode terminal regions. Therefore, a sufficient molten portion is formed in the anode terminal regions of all capacitor elements included in the laminate. That is, the bonding strength between the blade members and the anode terminal regions is improved. Therefore, a solid electrolytic capacitor with reduced ESR can be manufactured. Furthermore, due to the high bonding strength, a solid electrolytic capacitor with high thermal shock resistance can be manufactured.

[0018] The connection element for a solid electrolytic capacitor of the present invention includes a vane member and a terminal electrode connected to the vane member. The vane member has one end connected to the terminal electrode and the other end opposite the one end. The vane member is bent at a predetermined angle midway between the one end and the other end.

[0019] In this configuration, when the vane plate member is irradiated with a laser, a larger area of ​​the vane plate member faces the direction of the laser irradiation, which allows a larger area to be bonded to the capacitor element of the solid electrolytic capacitor, improving the bonding strength.

[0020] According to the present invention, it is possible to provide a solid electrolytic capacitor having improved bonding strength and high reliability.

[0021] FIG. 1(A) is an external perspective view of the solid electrolytic capacitor according to the first embodiment, and FIG. 1(B) is a cross-sectional view of the solid electrolytic capacitor according to the first embodiment. FIG. 2(A) is an enlarged view of a portion of the capacitor element according to the first embodiment, and FIG. 2(B) is a cross-sectional view of the capacitor element. FIG. 3(A) is an external view of a first external electrode, and FIG. 3(B) is a cross-sectional view of the first external electrode. FIG. 4 is a schematic diagram of the capacitor element according to the first embodiment. FIGS. 5(A) and 5(B) are schematic diagrams of the anode terminal region according to the first embodiment. FIGS. 6(A) and 6(B) are conceptual diagrams of the anode terminal region and the first external electrode joined together according to the first embodiment. FIG. 7 is a flowchart showing a procedure for forming the solid electrolytic capacitor according to the first embodiment. FIGS. 8(A) and 8(B) are cross-sectional views of the solid electrolytic capacitor according to the second embodiment. FIG. 9 is a schematic diagram of a capacitor element according to a third embodiment. 10A and 10B are conceptual diagrams showing the anode terminal area and the first external electrode joined together according to the fourth embodiment, and Fig. 11 is a conceptual diagram showing the anode terminal area and the first external electrode joined together according to the fifth embodiment.

[0022] [First Embodiment] A solid electrolytic capacitor 1 according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1(A) is an external perspective view of the solid electrolytic capacitor according to the first embodiment, and Fig. 1(B) is a cross-sectional view of the solid electrolytic capacitor according to the first embodiment.

[0023] (Structure of Solid Electrolytic Capacitor) The solid electrolytic capacitor 1 includes a capacitor assembly 10, a first external electrode 20, a second external electrode 30, and an insulating resin body 40. The first external electrode 20 includes a terminal electrode 21, a first blade plate member 22, and a second blade plate member 23. Note that in Figures 1(A) and 1(B), for ease of understanding, some components are omitted, and the insulating resin body 40 is shown in a see-through manner.

[0024] As shown in Figures 1(A) and 1(B), the capacitor assembly 10 includes a plurality of capacitor elements 11 and a conductive member 19. The conductive member 19 is preferably an electrode paste containing, for example, nickel, silver, or copper as a main component. The maximum thickness of the conductive member 19 is preferably 2 µm or more and 20 µm or less. Note that if conductivity equal to or greater than the desired conductivity can be obtained between the plurality of capacitor elements 11 without using the conductive member 19, the conductive member 19 can be omitted.

[0025] In this embodiment, there is no limitation on the number of capacitor elements 11 that make up the capacitor assembly 10, as long as they are plural. The structure of the capacitor elements 11 will be described in detail later.

[0026] The plurality of capacitor elements 11 are stacked. A capacitor assembly 10 (laminate) is formed by stacking the plurality of capacitor elements 11. At this time, the plurality of capacitor elements 11 are formed so as to be approximately parallel to each other.

[0027] The capacitor assembly 10 is sealed with an insulating resin body 40. This forms a sealed body 400. The sealed body 400 has a generally rectangular parallelepiped shape having a top surface 401, a bottom surface 402, a first surface 403, a second surface 404, a third surface 405, and a fourth surface 406. The first surface 403 is a surface opposite to the second surface 404, and the third surface 405 is a surface opposite to the fourth surface 406. The top surface 401 of the capacitor assembly 10 corresponds to the "first main surface" in the present invention, and the bottom surface 402 corresponds to the "second main surface" in the present invention.

[0028] The first external electrode 20 is formed along the sealing body 400 and a portion of the capacitor element 11. Specifically, the first external electrode 20 is disposed on the first surface 403 of the sealing body 400, a portion of the side surface of the capacitor element 11, and the bottom surface 402 of the sealing body 400. A more detailed structure of the first external electrode 20 will be described later. The first external electrode 20 corresponds to the "connection element of the solid electrolytic capacitor" of the present invention.

[0029] The first external electrode 20 includes a terminal electrode 21, a first blade plate member 22, and a second blade plate member 23 (see FIGS. 3A and 3B). The first external electrode 20 is made of, for example, a copper alloy or iron alloy material. The terminal electrode 21, the first blade plate member 22, and the second blade plate member 23 are physically and electrically connected. The first external electrode 20 is formed of, for example, a material cut out from a metal plate.

[0030] The terminal electrode 21, the first blade member 22, and the second blade member 23 may be integrally formed, and are preferably formed from a metal material that is easy to bend and has high conductivity. In this case, the first external electrode 20 is preferably arranged so as to be bent along the first surface 403 and the bottom surface 402 of the sealing body 400. The first blade member 22 and the second blade member 23 are preferably arranged so as to be bent along a portion of the capacitor element 11. The connection structure between the capacitor element 11 and the first external electrode 20 will be described in detail below.

[0031] The second external electrode 30 is formed along the sealing body 400. Specifically, the second external electrode 30 is disposed across the second surface 404 and the bottom surface 402. The capacitor element 11 and the second external electrode are joined with a conductive adhesive (not shown) made of silver paste or the like. Note that, like the first external electrode 20, the second external electrode 30 may be configured to include a blade member and a terminal electrode.

[0032] The connection layers (conductive layers including the solid electrolyte layer 113) of the plurality of capacitor elements 11 are electrically and physically connected to the second external electrode 30 by a conductive adhesive.

[0033] The second external electrode 30 is preferably formed from a metal material that is easy to bend and has high conductivity, such as a copper alloy or iron alloy. The second external electrode 30 is formed from a material cut out from a metal plate, for example. The first external electrode 20 and the second external electrode 30 may be made of the same material or different materials.

[0034] The insulating resin body 40 is mainly made of resin and may contain a filler. Examples of preferred resins include epoxy resin, phenol resin, polyimide resin, silicone resin, polyamide resin, and liquid crystal polymer. The resin may be in either solid or liquid form. It is preferred that corners are rounded by barrel polishing after resin sealing. Examples of preferred fillers include silica particles and alumina particles. The maximum diameter of the filler is preferably 30 μm or more and 40 μm or less. A material containing silica particles in a solid epoxy resin and phenol resin is more preferred.

[0035] (Structure of Capacitor Element) The structure of capacitor element 11 will be described in more detail with reference to FIGS. 2(A) and 2(B).

[0036] Fig. 2(A) is a plan view of capacitor element 11, and Fig. 2(B) is a cross-sectional view of capacitor element 11. Fig. 2(B) is a cross-sectional view taken along a plane (XZ plane) perpendicular to the flat film surface and end surface of capacitor element 11.

[0037] Capacitor element 11 includes electrode foil 111, dielectric layer 112, solid electrolyte layer 113, carbon layer 114, and metal layer 115. Electrode foil 111 includes electrode layer 111F and porous layer 111L.

[0038] A more specific structure of the electrode foil 111 is as follows. The electrode layer 111F is made of, for example, a metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, or silicon, or an alloy containing these metals. The electrode layer 111F is preferably made of aluminum or an aluminum alloy. A porous layer 111L is formed on the surface of the electrode layer 111F. The porous layer 111L is formed by etching the surface of the electrode layer 111F. This makes the porous layer 111L porous. The electrode foil 111 may be made of a valve metal that exhibits so-called valve action.

[0039] A dielectric layer 112 is formed on the electrode foil 111. As shown in FIGS. 2A and 2B , the electrode foil 111 has a first surface F1 and a second surface F2 that face each other in the Z-axis direction. The electrode foil 111 further includes a third surface F3, a fourth surface F4, a fifth surface F5, and a sixth surface F6 that are connected to the first surface F1 and the second surface F2 and parallel to the Z-axis direction. The third surface F3 and the fourth surface F4 are parallel to the Y-axis direction. The fifth surface F5 and the sixth surface F6 are parallel to the X-axis. The dielectric layer 112 covers the first surface F1, the second surface F2, the fourth surface F4, the fifth surface F5, and the sixth surface F6 of the electrode foil 111.

[0040] The dielectric layer 112 is preferably made of an oxide film of the electrode foil 111 (porous layer 111L). For example, when an aluminum foil is used for the electrode layer 111F, the dielectric layer 112 is formed by applying a voltage in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or their sodium salts or ammonium salts, and then anodizing the aluminum foil. The thickness of the dielectric layer 112 is preferably 10 nm or more and 100 nm or less.

[0041] Solid electrolyte layer 113 covers the outer surface of dielectric layer 112 (at least the surface opposite to the surface in contact with electrode foil 111). Solid electrolyte layer 113 also fills the numerous pores covered with dielectric layer 112.

[0042] More specifically, the solid electrolyte layer 113 includes, for example, an inner layer and an outer layer.

[0043] The inner layer is a layer of solid electrolyte layer 113 that abuts dielectric layer 112, and may be, for example, a PEDOT:PSS layer realized by a conductive polymer having a skeleton of pyrroles, thiophenes, anilines, or the like, or a conductive polymer having a skeleton of thiophenes such as PEDOT [poly(3,4-ethylenedioxythiophene)], and composited with polystyrene sulfonic acid (PSS) as a dopant. The inner layer is formed by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of dielectric layer 112 using an electrolyte solution that serves as the base for forming solid electrolyte layer 113, for example, a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or a method of applying a dispersion of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric portion and drying it.

[0044] The outer layer is a layer formed on the outside of the inner layer. For example, the outer layer is formed so as to cover the entire surface of the inner layer after the inner layer is formed to fill the fine recesses in the porous portion. The thickness of the outer layer is preferably 2 μm or more and 20 μm or less. The outer layer is formed by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of the inner layer using an electrolyte solution that serves as the base for forming the solid electrolyte layer 113, for example, a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or a method of applying a dispersion or paste of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the inner layer portion and drying it, or the like.

[0045] A conductive member may be provided as a layer subsequent to the outer layer. The conductive member may include, for example, a carbon layer and a silver layer. The carbon layer is preferably formed by applying a conductive paste containing a mixture of an insulating resin such as epoxy resin or phenolic resin and particles of carbon black or graphite. The silver layer is preferably formed by applying a conductive paste containing a mixture of an insulating resin such as epoxy resin or phenolic resin and particles of silver or the like. The materials constituting the conductive member may be appropriately combined, for example, by omitting the carbon layer.

[0046] The carbon layer 114 is formed so as to cover the outer layer (solid electrolyte layer 113). The carbon layer 114 contains a thermosetting resin. More specifically, the carbon layer 114 is formed by applying a carbon paste in which an insulating resin such as a phenolic resin is mixed with particles of carbon black or graphite.

[0047] The metal layer 115 is formed so as to cover the carbon layer 114. The metal layer 115 contains a thermoplastic resin. More specifically, the metal layer 115 is formed by applying a metal paste in which an insulating resin such as a phenolic resin is mixed with silver particles. The structures of the carbon layer 114 and the metal layer 115 will be described in more detail later.

[0048] With this configuration, capacitor element 11 becomes a flat-film solid electrolytic capacitor. In this capacitor element 11, electrode foil 111 corresponds to the anode, and solid electrolyte layer 113 corresponds to the cathode. The region of electrode foil 111 where solid electrolyte layer 113 is not formed corresponds to the "anode terminal region" in the present invention, and solid electrolyte layer 113 corresponds to the "cathode-forming region" in the present invention. Electrode foil 111 corresponds to the "main body" in the present invention.

[0049] (Detailed Structure of First External Electrode) Next, the structure of the first external electrode 20 will be described in detail with reference to FIGS. 3A and 3B. As shown in FIG. 3A, the first external electrode 20 includes a terminal electrode 21, a first blade plate member 22, and a second blade plate member 23. The terminal electrode 21 includes a side surface 231 and a bottom surface 232. As described above, the side surface 231 is disposed along the first surface 403, and the bottom surface 232 is disposed on the bottom surface 402 of the sealing body 400. The bottom surface 232 includes a first side surface 201 and a second side surface 202 facing the first side surface 201. The bottom surface 232 includes a third side surface 203 connected to the first side surface 201 and the second side surface 202 and parallel to the Z-axis direction, and a fourth side surface 204 facing the third side surface 203. The first blade plate member 22 is connected to the third side surface 203. The second slat member 23 is connected to the fourth side surface 204 .

[0050] 3(B) is a cross-sectional view of the first external electrode 20 in the XY plane including the first blade plate member 22 and the second blade plate member 23. The first blade plate member 22 has a first end 221 at one end connected to the third side surface 203 and a second end 222 at the other end. The first blade plate member 22 has a bent portion between the first end 221 and the second end 222. In other words, the first blade plate member 22 has a first blade plate inclined portion TP1 bent at a predetermined angle. The first blade plate member 22 is fixed to the bottom surface 232 of the terminal electrode 21 so that a portion of the first blade plate member 22 is inclined. The predetermined angle is preferably within the range of 20° to 60°.

[0051] Similarly, the second blade plate member 23 has a first end 223 at one end and a second end 224 at the other end, which are connected to the fourth side surface 204. The second blade plate member 23 has a bent portion between the first end 223 and the second end 224. In other words, the second blade plate member 23 has a second blade plate inclined portion TP2 that is bent to form a predetermined angle (the same predetermined angle as the first blade plate member 22 described above). The second blade plate member 23 is shaped so that it is fixed to the bottom surface 232 of the terminal electrode 21 so that a portion of it is inclined.

[0052] The first external electrode 20 is only required to include at least the terminal electrode 21, the first blade plate member 22, and the second blade plate member 23, and the shape thereof is not limited.

[0053] (Detailed Structure of Anode Terminal Region) Next, the detailed structure of the anode terminal region will be described with reference to Figures 4, 5(A), and 5(B). As described above, the anode terminal region AP is a region of the electrode foil 111 where the solid electrolyte layer 113 is not formed. As shown in Figure 4, it is preferable to provide an insulator layer 117 between the anode terminal region AP and the cathode formation region.

[0054] 4 is a plan view of the shape of the capacitor element 11 as viewed from the first face F1 side in FIGS. 2A and 2B, in other words, the XY plane. The anode terminal region AP has a first anode end portion 115a on the fifth face F5 side and a second anode end portion 115b on the sixth face F6 side. The first anode end portion 115a is formed over substantially the entire end surface of the anode terminal region AP on the fifth face F5 side. The second anode end portion 115b is formed over substantially the entire end surface of the anode terminal region AP on the sixth face F6 side.

[0055] As shown in FIG. 1B , a plurality of capacitor elements 11 are stacked. In the first anode end 115 a of the stacked capacitor elements 11, the area of ​​the anode terminal region AP is formed so as to increase stepwise along the first direction. Similarly, in the second anode end 115 b of the stacked capacitor elements 11, the area of ​​the anode terminal region AP is formed so as to increase stepwise along the first direction. More specifically, as shown in FIGS. 5A and 5B , the area of ​​the anode terminal region AP increases stepwise along the first direction. In other words, the first anode end 115 a and the second anode end 115 b of the anode terminal region of the capacitor assembly 10 are inclined along the first direction.

[0056] 5A, the area of ​​the anode terminal region AP of the capacitor element 11 increases stepwise in the first direction. That is, the area of ​​the anode terminal region AP in the XY plane increases stepwise in the order from the capacitor element 111a to the capacitor element 111e.

[0057] 5A is formed as follows: Capacitor element 11 is formed by stacking capacitor elements 111a, 111b, 111c, 111d, and 111e, each having a different length in the Y-axis direction of anode terminal area AP, along a first direction. As a result, anode terminal area AP in capacitor assembly 10 (laminate) has a stepped shape when viewed in the first direction.

[0058] 5B , the area of ​​the anode terminal region AP of the capacitor element 11 may be configured to increase in a slope-like manner along the first direction. That is, the areas of the capacitor elements 111a, 111b, 111c, 111d, and 111e in the XY plane may be configured to increase in stages in this order.

[0059] 5B is formed as follows. The capacitor elements 111a, 111b, 111c, 111d, and 111e are stacked to form the capacitor assembly 10 (laminate). The first anode end 115a of the capacitor assembly 10 is cut so as to have an incline when viewed in a first direction. Similarly, the second anode end 115b of the capacitor assembly 10 is cut so as to have an incline when viewed in the first direction.

[0060] That is, the first anode end 115a and the second anode end 115b in the capacitor element 111a to the capacitor element 111e are sloped when viewed in the first direction. In this case, the shape is not limited to a slope, and the anode end 115a and the second anode end 115b in the capacitor element 111a to the capacitor element 111e may be formed in an arc shape. When the anode end 115a and the second anode end 115b are formed in an arc shape, it is preferable that the ratio of the area increasing downward increases.

[0061] (Joint Shape of First External Electrode and Anode Terminal Region) The joint shape of the first external electrode 20 and the anode terminal region AP will be described using Figures 6(A) and 6(B). As shown in Figure 6(A), the first blade plate member 22 abuts against the first anode end portion 115a in the anode terminal region AP. That is, it is preferable that the inclination angles of the first blade plate inclined portion TP1 and the first anode end portion 115a are substantially the same. Furthermore, the second blade plate member 23 abuts against the second anode end portion 115b in the anode terminal region AP. That is, it is preferable that the inclination angles of the second blade plate inclined portion TP2 and the second anode end portion 115b are substantially the same.

[0062] Next, a structure for joining the first blade plate member 22 and the second blade plate member 23 to the anode terminal region AP will be described. As shown in Fig. 6(B) , the first blade plate member 22 is melted by irradiating a laser beam along the first direction at a location where the first blade plate inclined portion TP1 and the first anode end portion 115a abut. Similarly, the second blade plate member 23 is melted by irradiating a laser beam along the first direction at a location where the second blade plate inclined portion TP2 and the second anode end portion 115b abut. At this time, portions of the first anode end portion 115a and the second anode end portion 115b also melt.

[0063] The molten material formed by irradiating the area where the first blade inclined portion TP1 and the first anode end portion 115a abut with a laser drips down along the inclination of the first anode end portion 115a, so that a sufficient molten portion is formed in the first anode end portion 115a of the anode terminal region AP of every capacitor element included in the laminate.

[0064] The molten material formed by irradiating the area where the second blade inclined portion TP2 and the second anode end portion 115b contact each other with a laser drips down along the inclination of the second anode end portion 115b. Thus, a sufficient molten portion is formed in the second anode end portion 115b of the anode terminal region AP of every capacitor element included in the laminate.

[0065] That is, when the first blade member 22 and the second blade member 23 are irradiated with a laser beam in the first direction, the molten material drips down along the slope. Therefore, the first blade member 22 and the second blade member 23 are joined to the anode terminal region AP of each capacitor element included in the laminate by the molten portion, improving the bonding strength. This reduces the ESR of the solid electrolytic capacitor. Furthermore, the high bonding strength allows for a solid electrolytic capacitor that is resistant to thermal shock.

[0066] In the above-described configuration, both the first anode end 115a and the second anode end 115b are inclined. The first anode end 115a and the second anode end 115b are preferably symmetrical with respect to an axis. However, at least one of the first anode end 115a and the second anode end 115b may be inclined.

[0067] (Method of Manufacturing Solid Electrolytic Capacitor) The solid electrolytic capacitor 1 having the above-described configuration is manufactured, for example, as follows: Fig. 7 is a flowchart showing an example of a schematic flow of the method of manufacturing the solid electrolytic capacitor according to this embodiment.

[0068] The capacitor element 11 is formed (S11). Specifically, as shown in Figures 2(A) and 2(B), a dielectric layer 112, a solid electrolyte layer 113, a carbon layer 114, and a metal layer 115 are formed on a plurality of electrode foils 111.

[0069] Next, as shown in FIG. 1B, a conductive member 19 is formed on the solid electrolyte layer 113 of the capacitor element 11. The capacitor elements 11 are then stacked. At this time, as shown in FIG. 5A, the stacking is performed so that the first anode end 115a and the second anode end 115b in the anode terminal region of the capacitor element 11 have a stepped shape. Alternatively, as shown in FIG. 5B, a portion of the stack is cut so that the first anode end 115a and the second anode end 115b in the anode terminal region of the capacitor element 11 have a sloped shape. This forms the capacitor assembly 10 (S12).

[0070] 6(B), the first blade inclined portion TP1 is irradiated with a laser to join the first anode end portion 115a. Similarly, the second blade inclined portion TP2 is irradiated with a laser to join the second anode end portion 115b (S13).

[0071] Next, as shown in FIG. 1B, in the cathode forming region of the capacitor assembly 10, a conductive adhesive such as silver paste is used to bond to the second external electrode 30 (S14).

[0072] The capacitor assembly 10 is sealed with the insulating resin body 40 (S15). Specifically, as shown in Figures 1A and 1B, the capacitor assembly 10 is sealed with the insulating resin body 40 to form a sealed body 400.

[0073] Next, the terminal electrode 21 of the first external electrode 20 is bent along the first surface 403 and the bottom surface 402 of the sealing body 400. More specifically, the terminal electrode 21 of the first external electrode 20 is bent along the bottom surface 402 of the sealing body 400. Similarly, the second external electrode 30 is bent along the second surface 404 and the bottom surface 402 of the sealing body 400 (S16).

[0074] In the above-described structure, when the first blade member 22 and the second blade member 23 are irradiated with a laser in the first direction, the molten material drips along the slope between the first blade member 22 and the first anode end 115a, and between the second blade member 23 and the second anode end 115b. Therefore, a sufficient molten portion is formed in the first anode end 115a and the second anode end 115b of the anode terminal region AP of every capacitor element included in the laminate. This allows for the realization of a solid electrolytic capacitor 1 with reduced ESR. Furthermore, the high bonding strength allows for the formation of a solid electrolytic capacitor that is resistant to thermal shock.

[0075] Second Embodiment A solid electrolytic capacitor 1A according to a second embodiment of the present invention will be described with reference to the drawings. Figures 8A and 8B are schematic diagrams of a portion of the solid electrolytic capacitor 1A according to the second embodiment.

[0076] 8A and 8B, the solid electrolytic capacitor 1A according to the second embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in the positions where the vane plate members 22A are formed and the anode end portion 115c are formed. The other configurations of the solid electrolytic capacitor according to the second embodiment are the same as those of the solid electrolytic capacitor according to the first embodiment, and therefore, a description of the same parts will be omitted.

[0077] 8(A) and 8(B), the anode end 115c is formed at a position facing the first surface 403 of the capacitor assembly 10. In other words, the anode end 115c is formed at a position corresponding to the XZ plane. The anode end 115c has a shape that has a step in the first direction.

[0078] The vane plate member 22A is formed at a position facing the anode end portion 115c.

[0079] Even with this configuration, the molten material formed by irradiating the area where the first blade inclined portion TP1 and the anode end portion 115c abut with a laser drips down along the inclination of the anode end portion 115c. Therefore, a sufficient molten portion is formed in the anode end portion 115c of the anode terminal region AP of every capacitor element included in the laminate. In other words, the bonding strength between the blade member 22A and the anode terminal region is improved. This results in a solid electrolytic capacitor 1A with reduced ESR. Furthermore, the high bonding strength allows for the formation of a solid electrolytic capacitor that is resistant to thermal shock.

[0080] Third Embodiment A solid electrolytic capacitor 1B according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 9 is a schematic diagram of a solid electrolytic capacitor 1B according to the third embodiment.

[0081] 9, the solid electrolytic capacitor 1B according to the third embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in the shapes of the first anode end 116a and the second anode end 116b. The other configurations of the solid electrolytic capacitor according to the third embodiment are the same as those of the solid electrolytic capacitor according to the first embodiment, and a description of the same parts will be omitted.

[0082] The anode terminal region AP has a first anode end 116a on the fifth face F5 side and a second anode end 116b on the sixth face F6 side. The first anode end 116a is formed on a part of the end face of the anode terminal region AP on the fifth face F5 side. The second anode end 116b is formed on a part of the end face of the anode terminal region AP on the sixth face F6 side.

[0083] More specifically, the first anode end 116a is formed at approximately the center of the end face of the anode terminal area AP on the fifth face F5 side. In other words, the first anode end 116a is formed on a part of the end face of the anode terminal area AP on the fifth face F5 side. Similarly, the second anode end 116b is formed at approximately the center of the end face of the anode terminal area AP on the sixth face F6 side. In other words, the second anode end 116b is formed on a part of the end face of the anode terminal area AP on the sixth face F6 side.

[0084] Even with this configuration, the molten material formed by irradiating the area where the first blade inclined portion TP1 and the first anode end portion 116a contact with a laser drips down along the inclination of the first anode end portion 116a, and therefore a sufficient molten portion is formed in the first anode end portion 116a of the anode terminal region AP of every capacitor element included in the laminate.

[0085] Similarly, the molten material formed by irradiating the area where the second blade inclined portion TP2 and the second anode end portion 116 b contact each other with a laser drips down along the inclination of the second anode end portion 116 b. Thus, a sufficient molten portion is formed in the second anode end portion 116 b of the anode terminal region AP of every capacitor element included in the laminate.

[0086] In other words, the bonding strength between the blade plate member and the anode terminal region is improved, thereby realizing a solid electrolytic capacitor 1B with reduced ESR. Furthermore, the high bonding strength allows for the formation of a solid electrolytic capacitor that is resistant to thermal shock.

[0087] [Fourth Embodiment] A solid electrolytic capacitor 1C according to a fourth embodiment of the present invention will be described with reference to the drawings. Figures 10(A) and 10(B) are cross-sectional views of the solid electrolytic capacitor 1C according to the fourth embodiment.

[0088] 10A, the solid electrolytic capacitor 1C according to the fourth embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in that the area of ​​the anode terminal region AP of the capacitor element 11C is formed so as to gradually decrease in size along the first direction. The other configuration of the solid electrolytic capacitor according to the fourth embodiment is the same as that of the solid electrolytic capacitor according to the first embodiment, and a description of similar parts will be omitted.

[0089] In the first anode end 115a of the stacked capacitor element 11C, the area of ​​the anode terminal region AP is formed to decrease stepwise along the first direction. Similarly, in the second anode end 115b of the stacked capacitor element 11C, the area of ​​the anode terminal region AP is formed to decrease stepwise along the first direction.

[0090] 10A, the area of ​​the capacitor element 11C decreases stepwise in the first direction. That is, the area in the XY plane decreases stepwise from the capacitor element 111a to the capacitor element 111e.

[0091] When laser irradiation is performed in the above-described configuration, the solid electrolytic capacitor 1C is turned upside down on the Z axis as shown in FIG. 10(B).

[0092] As a result, the molten material formed by irradiating the area where the first blade inclined portion TP3 and the first anode end portion 115a abut with a laser drips down along the inclination of the first anode end portion 115a. Therefore, a sufficient molten portion is formed in the first anode end portion 115a of the anode terminal region AP of every capacitor element included in the laminate. In other words, the first blade member 22 and the capacitor element 111a are sufficiently joined.

[0093] Similarly, the molten material formed by irradiating the area where the second blade inclined portion TP4 and the second anode end portion 115 b abut against each other with a laser drips down along the inclination of the second anode end portion 115 b. Thus, a sufficient molten portion is formed in the second anode end portion 115 b of the anode terminal region AP of every capacitor element included in the laminate.

[0094] That is, when the laser is irradiated on the first vane plate member 22C and the second vane plate member 23C in the direction opposite to the first direction in the Z-axis direction, the molten material drips along the slope. This improves the bonding strength between the first vane plate member 22C and the second vane plate member 23C and the anode terminal area AP via the molten portion. This reduces the ESR of the solid electrolytic capacitor 1C. Furthermore, the high bonding strength allows for a solid electrolytic capacitor that is resistant to thermal shock.

[0095] Fifth Embodiment A solid electrolytic capacitor 1D according to a fifth embodiment of the present invention will be described with reference to the drawings. Fig. 11 is a cross-sectional view of the solid electrolytic capacitor 1D according to the fifth embodiment.

[0096] 11 , the solid electrolytic capacitor 1D according to the fifth embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in the positions where the first anode end 117 a and the second anode end 117 b are formed. The other configuration of the solid electrolytic capacitor according to the third embodiment is the same as that of the solid electrolytic capacitor according to the first embodiment, and a description of the same parts will be omitted.

[0097] The anode terminal region AP includes a first anode end 117a at approximately the center in the X-axis direction of the third face F3 (XZ plane) and a second anode end 117b on the sixth face F6 side. The first anode end 117a and the second anode end 117b are formed in parallel to each other along the Y-axis direction and at positions facing each other.

[0098] The first blade plate member 22D is formed to abut against the first anode end portion 117a, and the second blade plate member 23D is formed to abut against the second anode end portion 117b.

[0099] Even with this configuration, when the first blade plate member 22D is irradiated with a laser in the first direction in the above-described structure, the molten material drips along the slopes of the first blade plate member 22D and the first anode end portion 117a. Similarly, when the second blade plate member 23D is irradiated with a laser in the first direction, the molten material drips along the slopes of the second blade plate member 23D and the second anode end portion 117b. Therefore, a sufficient molten portion is formed in each capacitor element included in the laminate.

[0100] Furthermore, the configurations and various derivative examples shown in the above-described embodiments can be combined as appropriate, and effects corresponding to each combination can be achieved.

[0101] AP...anode terminal area F1...first surface F2...second surface F3...third surface F4...fourth surface F5...fifth surface F6...sixth surface TP1, TP3...first blade inclined portion TP2, TP4...second blade inclined portion 1, 1A, 1B, 1C, 1D...solid electrolytic capacitor 10...capacitor assembly 11, 11C...capacitor element 19...conductive member 20...first external electrode 21...terminal electrode 22, 22C...first blade member 23, 23C, 23D...second blade member 30...second external electrode 40...insulating resin body 111...electrode foil 111F...electrode layer 111a, 111b, 111c, 111d, 111e...capacitor element 111L...porous layer 112...dielectric layer 113...Solid electrolyte layer 114...Carbon layer 115...Metal layer 115a, 116a, 117a...First anode end 115b, 116b, 117b...Second anode end 115c...Anode end 117...Insulator layer 201...First side 202...Second side 203...Third side 204...Fourth side 221, 223...First end 222, 224...Second end 231...Side 232...Bottom 400...Sealing body 401...Top surface 402...Bottom surface 403...First surface 404...Second surface 405...Third surface 406...Fourth surface

Claims

1. A capacitor element comprising: a flat membrane-shaped main body containing a valve action metal and having a porous layer having a plurality of holes on a surface of the valve action metal; a dielectric layer formed on a cathode formation region; and a solid electrolyte layer formed on the dielectric layer, the capacitor element having an anode terminal region where the solid electrolyte layer is not formed on the main body, and the cathode formation region where the solid electrolyte layer is formed; a sealing body configured to seal a laminate in which a plurality of the capacitor elements are laminated with an insulating resin; a blade member and a terminal electrode connected to the blade member, a first external electrode connected to the anode terminal region; and a second external electrode connected to the cathode formation region, the laminate having a first main surface parallel to the capacitor element and a second main surface opposite to the first main surface, at least a portion of the anode terminal region is formed so that its area changes stepwise in a first direction parallel to a direction from the first main surface to the second main surface when the capacitor element is viewed in a plane, the blade member being formed along the anode terminal region, a solid electrolytic capacitor, wherein the anode terminal area and the blade plate member are joined via a fusion portion of the anode terminal area or the blade plate member.

2. The solid electrolytic capacitor according to claim 1, wherein the shape of the side surface in the anode terminal area changes in a stepped manner.

3. The solid electrolytic capacitor according to claim 1, wherein the shape of the side surface in the anode terminal area changes into a sloping shape.

4. The solid electrolytic capacitor according to claim 1, wherein the shape of the side surface in the anode terminal area changes into an arc shape.

5. The solid electrolytic capacitor according to claim 1, wherein the area of ​​the anode terminal region is formed so as to increase stepwise in the first direction.

6. The solid electrolytic capacitor according to claim 1, wherein the area of ​​the anode terminal region is formed so as to decrease stepwise in the first direction.

7. A capacitor element forming process for forming a capacitor element having a flat membrane-like main body containing a valve metal and having a porous layer with a plurality of holes on a surface of the valve metal, a dielectric layer formed on a cathode formation region, and a solid electrolyte layer formed on the dielectric layer, the capacitor element having an anode terminal region on the main body where the solid electrolyte layer is not formed, and the cathode formation region where the solid electrolyte layer is formed; a sealing body forming process having a configuration in which a laminate in which a plurality of the capacitor elements are stacked is sealed with an insulating resin; a first external electrode forming process for forming a first external electrode having a blade member and a terminal electrode connected to the blade member and connected to the anode terminal region; and a second external electrode forming process for forming a second external electrode connected to the cathode formation region, wherein in the capacitor element forming process, a first main surface of the laminate parallel to the capacitor element and a second main surface opposite to the first main surface, at least a portion of the anode terminal region is formed so that its area changes stepwise in a first direction parallel to the direction from the first main surface to the second main surface when the capacitor element is viewed in a plane, the blade member is formed along the anode terminal region, and the anode terminal region and the blade member are joined via a molten portion formed by irradiating the blade member with a laser.

8. A connection element for a solid electrolytic capacitor comprising a blade member and a terminal electrode connected to the blade member, the blade member having one end connected to the terminal electrode and another end opposite to the one end, and bent at a predetermined angle midway between the one end and the other end.

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